FR3127337A1 - Circulating batteries with a negolyte based on viologen and a hydro-alcoholic solvent. - Google Patents

Abstract

The present invention relates to a circulating electrochemical system comprising a posolyte and a negolyte in which said negolyte comprises a viologenic compound and at least one carrier salt, in a hydroalcoholic solution comprising more than 50% water and comprising at least 5% alcohol by volume, said alcohol being miscible in water in the chosen proportions. Figure 1 to be published

Description

Circulating batteries with a negolyte based on viologen and a hydro-alcoholic solvent.

The invention relates to the field of electrochemical storage, more particularly that of flow-through batteries comprising two liquid electrolytes.

The circulation battery is an electrochemical storage technology whose general principle is described in the . The circulation battery or RFB (for "Redox Flow Battery") is able to store electrical energy when it is, for example, produced by wind turbines or solar panels, to store it, then to release it. a posteriori on the electrical network. A flow-through battery consists of two compartments comprising a negative liquid electrolyte and a positive liquid electrolyte also called respectively negolyte and posolyte, between which a transfer of ions (1) takes place through an ion exchange membrane (2). Each of the compartments contains a porous electrode (3). Liquid electrolytes consist of at least one solvent (water or organic solvent), one or more electroactive species and a support salt making it possible to increase the ionic conductivity of the medium. More specifically, the two electrolytes are each pumped from a reservoir (positive electrolyte reservoir (4) and negative electrolyte reservoir (5)) to an elementary cell (6) consisting of two compartments separated by said ion exchange membrane (2 ). This membrane prevents the two electrolytes from mixing, but allows the transfer of small ions between the solutions to maintain electrical neutrality. The compartments each contain an electrode, most often porous, where the electrochemical reactions will take place:

• during charging, electrical energy is supplied to the battery via an inverter/charger (7), the electroactive species of the negolyte are reduced and those of the posolyte oxidize by exchanging electrons via the electrical circuit,
• during a discharge, the reverse reactions take place by restoring the electrical energy and exchanging the electrons via the electrical circuit.

Whatever the system, electrical losses occur because of ohmic losses due to the electrical resistance of the different materials, the kinetics of electrochemical reactions, the diffusion of species and the energy used by the pumps. Today the best commercial batteries manage to achieve energy yields of 70 to 80%.

Circulating batteries, unlike other solid-state batteries, have the advantage of being able to decorrelate their power from their capacity. Indeed, their capacity will be directly related to the volume of the electrolytes and their power to the surface of the cells and to their number. These batteries are therefore suitable for long-term storage (from several hours to several days) and for large capacities (several MWh).

The best known circulating batteries are based on vanadium. The competitiveness of this technology is currently limited by the volatility of the price of vanadium, its toxicity and the very corrosive pH conditions necessary to ensure good solubility of the electroactive species. It has therefore been envisaged to replace the vanadium by organic electroactive species. The large existing variety of molecules and the significant potential for synthesis make it possible to envisage molecules that are inexpensive to produce, without rare elements, possibly biosourced, easily recyclable and with electrochemical performances of the same order of magnitude, or even better than vanadium batteries. .

The properties of aqueous organic electrolytes are interesting. Indeed, organic solvents are highly limited in ionic conductivity, which has the consequence of limiting the power of the battery. In addition, these solvents bring additional safety constraints, particularly in terms of flammability.

A molecule of interest for organic circulation batteries in an aqueous medium must have the following properties:

• An adapted electrochemical potential,
• Fast kinetics,
• rapid dissemination,
• High solubility (with if possible several electrons exchanged per molecule),
• High stability,
• An absence of diffusion through the membranes,
• A low synthetic price.

An ideal molecule is therefore a compromise between several often conflicting properties.

These properties are also sought for active molecules used as organic electrodes in lithium batteries. The difference is that the molecules must instead be insoluble in organic solvents, which often amounts to molecules that are very soluble in water.

Violinogens have been studied for flow-through batteries for some years. Utah State University patent applications US2018072669 and US2020168910 describe the use of the viologen family and 4,4'-bipyridine derivatives in aqueous circulating battery negolytes. Only viologens with methyl, trimethylaminepropyl and sulfopropyl groups were tested in an electrolyte comprising water as solvent. The behavior of these viologens in a purely aqueous medium has subsequently been detailed in the literature (see references 1 to 8). Patent CN111244518 specifically describes the use of viologens (in particular methyl viologen) in an electrolyte with potassium bromide and with a bromine-based posolyte. The use of viologens in flow-through batteries has also been mentioned in patent application WO19245461. In the latter, the viologenic compound is associated with a solid redox species and serves as a mediator between the electrochemical cell and the solid stored in a reservoir. In addition, viologens are also cited in patent US10424806, but as an electrolyte for organic solvent circulation batteries.

A. Jouhara, E. Quarez, F. Dolhem, M. Armand, N. Dupré, P. Poizot, Angew. Chem. Int. Ed. 16 (2019) 859 described viologenic diacetate as an electroactive molecule for solid organic anion-ion batteries.

Unexpectedly, the Applicant discovered that the use of a negolyte comprising:

-a viologen-type compound of formula (I),

With L ₁ and L ₂ each independently selected from the groups consisting of the chains C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkenyl, C ₁ -C ₁₂ alkynyl and C ₁ -C ₄ alkyl-(OCH ₂ CH ₂ ) _n , R ₁ and R ₂ are independently selected from -H, -NO ₃ , -OR ₃ , -N(R ₃ ) _m , -C(O)R ₃ , -C(O)OR ₃ , -S( O) _m , -PO ₃ , -S(O) _m R ₃ , -OP(O)(OR ₃ ) ₂ , -OCH ₂ , -(C(R ₃ ) ₂ CN, substituted aryl and substituted heteroaryl, wherein R ₃ is at each occurrence independently selected from -H, alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, alkyl-N(R ₄ ) _m , alkyl-S(O) _m , an oxygen protecting group and an protecting group and R ₄ at each occurrence is independently selected from -H , alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, an oxygen protecting group and a nitrogen protecting group,

-at least one support salt necessary for sufficient ionic conductivity and the transfer of charge in ionic form through the membrane during the charging and discharging cycles of the battery, the support salt coming either from the salt associated with the viologen, or from added salt, or both.

-and a hydro-alcoholic solvent with a water content greater than or equal to 50%;

made it possible to obtain batteries (or electrochemical systems) with interesting properties and which make it possible in particular to solve the drawbacks of the systems of the prior art.

The term “nitrogen protecting group” means substituents which can be introduced to protect the functional groups containing nitrogen (for example —NH ₂ or NHR) from undesirable reactions. The nitrogen protecting groups can in particular be chosen from the following compounds: p-methoxyphenyl ("PMP"), benzyl, methyl, triphenylmethyl, pivaloyl, pyrrolidinylmethyl, t-butoxycarbonyl, silyl, acetyl, benzyloxycarbonyl (Cbz) and trimethylsilyethoxymethyl (SEM ).

By "oxygen-protecting group" is meant substituents which can be introduced to protect the functional groups containing oxygen (for example -OH) from undesirable reactions. The oxygen protecting groups can in particular be chosen from silyl ethers, methyl ethers, alkyl ethers, benzyl ethers, esters, benzoates, carbonates and sulphonates.

Bibliographic references

1. C. DeBruler, B. Hu, J. Moss, X. Liu, J. Luo, Y. Sun, T.L. Liu, Chem 3 (2017) 961–978.

2. C. DeBruler, B. Hu, J. Moss, J. Luo, T.L. Liu, ACS Energy Lett. 3 (2018) 663–668.

3. E.S. Beh, D. de Porcellinis, R.L. Gracia, K.T. Xia, R.G. Gordon, M.J. Aziz, ACS Energy Lett. 2 (2017) 639–644.

4. B. Hu, C. DeBruler, Z. Rhodes, T.L. Liu, J. Am. Chem. Soc. 139 (2017) 1207–1214.

5. B. Hu, C. Seefeldt, C. DeBruler, T.L. Liu, J. Mater. Chem. A5 (2017) 22137–22145.

6. B. Hu, Y. Tang, J. Luo, G. Grove, Y. Guo, T.L. Liu, Chemical communications (Cambridge, England) 54 (2018) 6871–6874.

7. T. Liu, X. Wei, Z. Nie, V. Sprenkle, W. Wang, Adv. Energy Mater. 6 (2016) 1501449.

8. Y. Liu, Y. Li, P. Zuo, Q. Chen, G. Tang, P. Sun, Z. Yang, T. Xu, ChemSusChem (2020).

9. A. Jouhara, E. Quarez, F. Dolhem, M. Armand, N. Dupré, P. Poizot, Angew. Chem. 16 (2019) 859.

The invention relates to a circulating electrochemical system comprising a posolyte and a negolyte, in which said negolyte comprises a viologenic compound of formula (I) and at least one carrier salt in a hydroalcoholic solution comprising more than 50% water and comprising at least 5% alcohol by volume, said alcohol being miscible in water in the chosen proportions,

With L ₁ and L ₂ each independently selected from the groups consisting of alkyl chains comprising from 1 to 12 carbon atoms, alkenyl chains comprising from 1 to 12 carbon atoms, alkynyl chains comprising from 1 to 12 carbon atoms and alkyl-(OCH ₂ CH ₂ ) _{n chains, the} alkyl chain comprising from 1 to 4 carbon atoms, R ₁ and R ₂ being selected independently from the groups -H, -NO ₃ , -OR ₃ , -N(R ₃ ) _m , -C(O)R ₃ , -C(O)OR ₃ , -S(O) _m , -PO ₃ , -S(O) _m R ₃ , -OP(O)(OR ₃ ) ₂ , -OCH ₂ , -(C(R ₃ ) ₂ CN, substituted aryl and substituted heteroaryl, R ₃ being at each occurrence selected independently from the groups -H, alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, alkyl-N(R ₄ ) _m , alkyl-S(O) _m , an oxygen protecting group and a nitrogen protecting group, R ₄ at each occurrence being independently selected from -H , alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, a oxygen protecting group and a nitrogen protecting group.

Said hydroalcoholic solution may comprise at least one alcohol chosen from: methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, tert -butanol, isobutanol, phenol, ethylene glycol.

Said at least one alcohol can be chosen from isopropanol, ethanol, tert-butanol, and methanol.

The alcohol concentration in the hydro-alcoholic solution may be greater than or equal to 10% by volume, preferably greater than or equal to 20% by volume.

Said viologenic compound can be chosen from viologenic N,N' diacetate, viologenic N,N'-dimethyl, viologenic N,N'-disulfopropyl and viologenic N-acetate-N'-sulfopropyl.

Said posolyte may comprise at least one compound chosen from the following compounds: potassium ferrocyanide or lithium, potassium or sodium TEMPO sulfate, or bis ((3-trimethyl ammonio) propyl) ferrocene, alone or in a mixture, in aqueous solution or in hydroalcoholic solution.

Said posolyte may also also contain at least one carrier salt in solution.

Said at least one support salt of the negolyte and/or of the posolyte can be chosen from the salts of formula AB in which A is a cation chosen from Na ⁺ , K ⁺ , Li ⁺ , NR ₄ ⁺ , R-pyridinium, R-pyrrolidium , or R-imidazolium; R being a hydrogen, alkyl, cycloalkyl, heterocyclyl, aryl, or heteroaryl radical; And
B is an anion selected from F ^- , Cl ^- , Br ^- , SO ₄ ^2- , SO ₃ ^2- , BO ₃ ^3- , B ₄ O ₇ ^2- , OH ^- , CO ₃ ^2- , ClO ₄ ^- , H ₂ PO ₄ ^- , HPO ₄ ^2- , PO ₄ ^3- , NO ₃ ^- , N ₃ ^- , CN ^- , -N(CN) ₂ ^- , SCN ^- , CH ₃ OSO ₃ ^- , CH ₃ SO ₃ ^- said au least one support salt preferably being chosen from NaCl, KCl, or NH ₄ Cl.

The concentration of support salt(s) in each of said negolyte and optionally of said posolyte may be between 0.5 M and 4 M, very preferably between 0.8 M and 2 M, relative to the total volume of negolyte and/or posolyte.

The concentration of viologenic compound of formula (I) in said negolyte can be between 0.1 M and 2 M, preferably between 0.3 and 1 M relative to the total volume of negolyte.

The electrochemical system according to the invention may comprise:

-a posolyte tank (4)

-a negolyte tank (5)

- an elementary cell (6) consisting of two compartments separated by an ion exchange membrane (2) respectively comprising said negolyte and said posolyte,

- a porous electrode (3) in each compartment.

List of Figures

[Fig 1]

There represents the diagram of operation of a circulating battery.

[Fig 2]

There represents examples of viologenic compounds.

Figure 2a shows the chemical formula of 4,4'-bipyridine.

Figure 2b depicts the mechanism by which viologen-like compounds can exchange two electrons by reducing to an intermediate radical form.

Figures 2c to 2f show examples of compounds with a viologenic unit that can be used in the negolyte of flow-through batteries according to the invention: N,N'-dimethylviologen MV (c), N,N'-disulfopropyl viologen SPrV (d) , the viologenic N,N'-diacetate AcV (e) and the viologenic N-acetate-N'-sulfopropyl AcSPrV (f).

[Fig 3]

There presents a cyclic voltammetry curve of a battery according to example 1 with a negolyte based on 1 mM viologenic N,N'-diacetate with 1 M KCl in pure water (comparative, in solid lines) and in a hydroalcoholic solution corresponding to an 80/20 volume water/isopropanol mixture (according to the invention, in dotted lines).

[Fig 4]

There shows a charge and discharge cycle (for a circulating battery according to Example 1 with a solution of 50 mL of 0.4 M viologenic N,N'-diacetate and 1 M KCl in a) pure water (comparative ) and b) an 80/20 vol vs. water/isopropanol mixture. 0.4 M ferrocyanide in 1 M KCl as posolyte (according to the invention).

[Fig 5]

There presents a bar diagram of 20 charge-discharge cycles for a circulating battery according to example 1 N,N'-viologenic diacetate AcV/Ferrocyanide for cells containing pure water (comparative) and a water/isopropanol mixture 80/20 vol (according to the invention).

[Fig 6]

There presents the capacities over three cycles of two circulating batteries according to example 1 AcV N,N'-diacetate viologen / TEMPO potassium sulphate with a negolyte whose solvent is pure water (comparative) and whose solvent is a water/isopropanol mixture 80/20 vol. (according to the invention), operated under the same conditions.

[Fig 7]

There presents the cyclic voltammetry of a flow-through battery according to Example 2 comprising 1 mM N,N'-disulfopropyl viologen with 1M KCl in pure water (comparative) and an 80/20 vol water/isopropanol mixture (according to the 'invention).

[Fig 8]

There presents the charging capacity C and discharging capacity D cycle by cycle N of batteries according to example 2 with a solution of 100 mL of 0.4 M ferrocyanide and 1 M KCl in pure water as posolyte and a 90 mL solution of N,N'-disulfopropyl viologen 0.4 M and KCl 1 M in water (1C and 1D) and in an 80/20 vol v s water/isopropanol mixture . 0.4 M ferrocyanide in 1 M KCl as posolyte (2C and 2D).

[Fig 9]

There presents the cyclic voltammetry of a flow-through battery according to Example 3 with 1 mM N,N'-dimethyl viologen with 1 M KCl in pure water (comparative, curve with X symbols), a water/ tert -butanol 95/05 vol (○) and 80/20 vol (□).

[Fig 10]

There shows the charging of a battery according to Example 3 with N,N'-dimethyl viologen as negolyte in solution in a) water and b) an 80/20 vol water/ tert -butanol mixture (Ubatt (X) and I( ) The conditions are: Umax = 1 V and I = 500 mA with a solution of 100 mL of 0.4 M ferrocyanide and 1 M KCl in pure water as posolyte and a solution of 90 mL of N,N 0.4 M '-dimethyl viologen and 1 M KCl in a) water (comparative) and b) an 80/20 vol water/tert-butan-2-ol mixture (according to the invention).

[Fig 11]

There presents the cyclic voltammetry of a battery according to example 4 with 1 mM N,N'-dimethyl viologen with 1M KCl in pure water (comparative, curve with the symbols x ) and in a water/isopropanol mixture 95/ 05 vol (○), 90/10 vol (□) and 80/20 vol (+).

[Fig 12]

There presents the cyclic voltammetry of a battery according to example 5 of N,N'-dimethyl viologen at 1 mM with KCl 1M in pure water (comparative, curve with the symbols x ) and a water/ethanol mixture 95/05 vol (○), 90/10 vol (□) and 60/40 vol (+).

[Fig 13]

There presents the cyclic voltammetry of a battery according to Example 6 with 1 mM N,N'-dimethyl viologen with 1M KCl as support salt, in pure water (comparative, curve with the symbols x) and a water/ 80/20 vol methanol (according to the invention, ○).

[Fig 14]

There presents the cyclic voltammetry of a battery according to example 7 with 1 mM N,N'-dimethyl viologen with 1M KCl in pure water (comparative, curve with the x's) and a water/butan-2-ol mixture 91/9 vol (according to the invention, ○).

Claims (11)

Circulating electrochemical system comprising a posolyte and a negolyte in which said negolyte comprises a viologenic compound of formula (I) and at least one carrier salt in a hydroalcoholic solution comprising more than 50% water and comprising at least 5% alcohol by volume, said alcohol being miscible in water in the chosen proportions,

With L ₁ and L ₂ each independently selected from the groups consisting of alkyl chains comprising from 1 to 12 carbon atoms, alkenyl chains comprising from 1 to 12 carbon atoms, alkynyl chains comprising from 1 to 12 carbon atoms and alkyl-(OCH ₂ CH ₂ ) _n chains _{, the} alkyl chain comprising from 1 to 4 carbon atoms, R ₁ and R ₂ being selected independently from the groups -H, -NO ₃ , -OR ₃ , -N(R ₃ ) _m , -C(O)R ₃ , -C(O)OR ₃ , -S(O) _m , -PO ₃ , -S(O) _m R ₃ , -OP(O)(OR ₃ ) ₂ , -OCH ₂ , -(C(R ₃ ) ₂ CN, substituted aryl and substituted heteroaryl, R ₃ being at each occurrence selected independently from the groups -H, alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, alkyl-N(R ₄ ) _m , alkyl-S(O) _m , an oxygen protecting group and a nitrogen protecting group, R ₄ at each occurrence being independently selected from -H , alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, a oxygen protecting group and a nitrogen protecting group. Circulating electrochemical system according to Claim 1, in which the said hydroalcoholic solution comprises at least one alcohol chosen from: methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, tert -butanol, isobutanol, phenol, ethylene glycol. Electrochemical system according to Claim 2, in which the said at least one alcohol is chosen from isopropanol, ethanol, tert -butanol, and methanol. Electrochemical system according to one of the preceding claims, in which the alcohol concentration in the hydro-alcoholic solution is greater than or equal to 10% by volume, preferably greater than or equal to 20% by volume. Electrochemical system according to one of Claims 1 to 4, in which the said viologenic compound is chosen from N,N' diacetate viologen, N,N'-dimethyl viologen, N,N'-disulfopropyl viologen, and N-acetate- N'-sulfopropyl viologen. Circulating electrochemical system according to one of the preceding claims, in which the said posolyte comprises at least one compound chosen from the following compounds: potassium ferrocyanide or lithium, potassium or sodium TEMPOsulfate, or bis ((3-trimethyl ammonio) propyl) ferrocene, alone or as a mixture, in aqueous solution or in hydroalcoholic solution. Electrochemical system according to one of Claims 1 to 6, in which the said posolyte contains at least one carrier salt in solution. Electrochemical system according to one of Claims 1 to 7, in which the said at least one support salt of the negolyte and/or of the posolyte is chosen from the salts of formula AB in which A is a cation chosen from Na ⁺ , K ⁺ , Li ⁺ , NR ₄ ⁺ , R-pyridinium, R-pyrrolidium, or R-imidazolium; R being a hydrogen, alkyl, cycloalkyl, heterocyclyl, aryl, or heteroaryl radical; and B is an anion selected from F ^- , Cl ^- , Br ^- , SO ₄ ^2- , SO ₃ ^2- , BO ₃ ^3- , B ₄ O ₇ ^2- ,OH ^- , CO ₃ ^2- , ClO ₄ ^- , H ₂ PO ₄ ^- , HPO ₄ ^2- , PO ₄ ^3- , NO ₃ ^- , N ₃ ^- , CN ^- , -N(CN) ₂ ^- , SCN ^- , CH ₃ OSO ₃ ^- , CH ₃ SO ₃ ^- , said at least one support salt preferably being chosen from NaCl, KCl, or NH ₄ Cl. Electrochemical system according to one of Claims 1 to 8, in which the concentration of carrier salt(s) in each of said negolyte and optionally of said posolyte is between 0.5 M and 4 M, very preferably between 0. 8 M and 2 M, relative to the total volume of negolyte and/or posolyte. Electrochemical system according to one of the preceding claims, in which the concentration of viologenic compound of formula (I) in the said negolyte is between 0.1 M and 2 M, preferably between 0.3 and 1 M with respect to the total volume of negolyte. Electrochemical circulation system according to one of the preceding claims comprising:
-a posolyte tank (4)
-a negolyte tank (5)
- an elementary cell (6) consisting of two compartments separated by an ion exchange membrane (2) respectively comprising said negolyte and said posolyte,
- a porous electrode (3) in each compartment.